Publisher Summary This chapter reviews the existing data on numbers of chemoreceptors on the legs, mouthparts, and antennae of insects and describes the physiological characteristics of the sensilla. It discusses the possible significance of numbers of sensilla in relation to insect behavior and evolution. The picture that emerges is fragmentary, but the fragments should serve to indicate fruitful lines of research, which will lead to a better understanding of the physiological significance of chemoreceptor populations and the numerical differences that occur between them. It is apparent that observed behavior will often be the outcome of interactions between several, even many, chemosensory inputs. It is not, therefore, to be expected that the input from a single receptor will be directly related to behavior except in very simple situations. This may be true even where a receptor is tuned to a key stimulus. For example, bark beetles have very few olfactory sensilla compared with many moths and, as a consequence, they are probably less sensitive to their attractant pheromone. However, bark beetle pheromones are produced at host trees that have a characteristic odor. This is also attractant to the beetles and occurs in much greater concentrations than the pheromone so that attraction from a distance can occur without a very sensitive sensory system.

Chemoreception: The Significance of Receptor Numbers

List of contributors. Preface. Part One: Monitoring distribution and abundance. 1. Butterfly monitoring 1 - recording the changes P.T. Harding, et al. 2. Butterfly monitoring 2 - interpreting the changes E. Pollard, B.C. Eversham. 3. Butterfly mobility T.G. Shreeve. 4. Ecology and conservation of butterfly metapopulations in the fragmented British landscape C.D. Thomas. Part Two: Butterflies and land use in Britain. 5. Butterflies on nature reserves in Britain I.F.G. McLean, et al. 6. Butterfly conservation on arable farmland R.E. Feber, H. Smith. 7. Butterfly conservation within the management of grassland habitats M.R. Oates. 8. Woodland management and butterfly diversity P.A. Robertson, et al. 9. Gardens: the neglected habitat M.L. Vickery. Part Three: Managing endangered species. 10. The ecology and conservation of Papilio machaon in Britain J.P. Dempster. 11. Ecology and conservation of Lycaena dispar: British and European perspectives A.S. Pullin, et al.12. The conservation of Carterocephalus palaemon in Scotland N.O.M. Ravenscroft. 13. The ecology and conservation of Maculinea arion and other European species of large blue butterfly J.A. Thomas. 14. Managing local microclimates for the high brown fritillary, Argynnis adippe M.S. Warren. Part Four: European and global perspectives. 15. Implications of biogeographical structures for the conservation of European butterflies R.L.H. Dennis, W.R. Williams. 16. Measuring changes in butterfly abundance in The Netherlands C.A.M. van Swaay. 17. Conservation of butterflies in Central Europe O. Kudrna. 18. Ecology and conservation of alpine Lepidoptera A. Erhardt. 19. Conservation of butterfly habitats and diversity in European Mediterranean countries M.L. Munguira. 20. Butterfly biodiversity and conservation in the Afrotropical region T.B. Larsen. 21. Butterfly conservation in Australasia -- an emerging awareness and an increasing need T.R. New. 22. Conservation and management of butterfly diversity in North America P.A. Opler. References. Butterfly species index. Subject index.

Ecology and conservation of butterflies

How do insect and plant species numbers change with respect to one another at a regional scale? Evidence for three higher insect taxa suggest that the patterns may vary substantialIy from one group to another. Estimates of the total numbers of insect species in different countries suggest that overall there may be a tendency for ratios of insect-to-plant species to be low when plant richness per unit area is high. Regional insect-to-plant ratios are very variable. For particular higher insect taxa global ratios of insect-to-plant species fall within the range of regional ratios, suggesting that regional ratios of all insects to plants may provide a means of estimating the global number of insect species

Regional numbers of insect and plant species

Evidences from fossil records and genetic research suggest that the arboreal refugia were not restricted to Southern Europe and in particular to the Mediterranean peninsulas during the full-glacials. Fossil pollen data and macrofossil remains indicate that several tree species have survived also at the Southern edge of the cold-dry steppe-tundra area in Central and Eastern Europe. Recent results of surveys on the Late Pleistocene Mammalian fauna clearly contradict to the “tree-less tundra” models for Europe North of the transverse mountain ranges of the Pyrenees, Alps and Carpathians. It was pointed out that the carrying capacity to feed the herds of large herbivores demands a rather productive environment. The presence of Northern temperate refugia is also supported by the “non-analogue” assemblages of small mammals discovered from the Late Pleistocene of unglaci­ated areas of Eastern Central Europe. The assembly of species today typifying the tundra, steppe and semi-desert habitats seems to include also species from deciduous woodland. Extra-Mediterranean core areas were identified also in widely dispersed cold-tolerant frogs and reptiles. Some of their core areas had been at least near the Carpathians and/or marginal areas of the Carpathian Basin. The close faunal connections of the Carpathians suggest the existence of highly dynamic contacts and exchanges with mountains of the Balkan Peninsula during the climatic fluctuations of the Upper Pleistocene. The Eastern and Southern Carpathians, together with the mountains of Western Transylvania, can be considered as core areas of survival and autochtonous evolution in some invertebrate groups with limited mobility. The post-glacial re-population of the Carpathian Basin from different directions has been supported by Illyrian versus Dacian vicarious pairs of sister species/subspecies. In mobile insect groups, peripherically isolated sibling species/subspecies have only been evolved, which display manifold biogeographic connections, e.g. to the Balkan Peninsula, Asia Minor or Southern Russia. The organisation of community-complexes of the Pannonian forest-steppe connected by habitat ecotones resulted in the overlap of several different faunal types, e.g. Mediterranean, Balkanic, Siberian, Ponto-Caspian, Ponto-Pannonian, Turano-Eremic and Xeromontane elements.

Extra-Mediterranean Refugia, Post-Glacial Vegetation History and Area Dynamics in Eastern Central Europe

Several aspects of estimating what happened when and where in the evolution of the Lepidoptera are discussed. Because of their scarcity and often poor preservation, fossils are not very helpful, but at least they demonstrate that, in the Oligocene some taxa of butterflies, perhaps at tribal level or higher, did occur in the Northern as well as in the Southern Hemisphere. The concept of a molecular clock is seen as a most needed test for vicariance explanations of disjunct distributions. Special emphasis is laid on the importance of calibration of the clock. The use of geological vicariance events as calibration points is rejected, because of circularity when vicariance explanations are to be tested. Fossils as calibration points should ideally be replaced by the minimum age of an apomorphous character state demonstrated by the fossil rather than a supposed identity on the basis of overall similarity. Some conditions that directed the evolution of Lepidoptera (called constraints here) are discussed for their possible use as calibration points. Estimation of the evolution in space through time (palaeobiogeography) as found in recent literature is discussed, the often supposed role (of the break-up) of Gondwana in the evolution of the butterflies is challenged, and an alternative hypothesis is given. R. de Jong, National Museum of Natural History, P.O. Box 9517, 2300 RA Leiden, The Netherlands. E-mail: jong@naturalis.nnm.nl

Andrzej Samuel Kostrowicki

Papers

Geography of the palaearctic Papilionoidea (Lepidoptera)